1. Field of the Invention
The present invention pertains to an improvement in water cannons, and more particularly to water cannons used to render safe explosive devices. The present invention improves the performance of such systems, particularly related to their use to render safe explosive devices.
2. Description of the Related Art
Presently, devices using water to disrupt detonation of explosive devices are widely used. This is because of the relatively low velocity and density of a water jet. These devices  normally comprise a slug of water contained within a tube between a burst diaphragm and an obturated pusher plate or piston. When pressure is applied to the pusher plate or piston, the burst diaphragm ruptures and a jet of water issues from the device. Pressure to the pusher plate or piston is normally applied by burning a gun propellant that is housed in a cartridge or as a breech charge. The propellant can be ignited electrically, mechanically, or through other means. Electrical initiation of the firing train may start with a planar bridge element, electric match, squib, or shock tube. Mechanical initiation may begin with a primer or flueric device.
One such device, known as a JROD (jet remote operating device), was developed by the United States Navy to render safe improvised explosive devices at close range. The JROD uses the principles named above to supply approximately 600 ft/sec of water to accomplish this task. However, because the back portion of the water slug in the JROD, and other water disrupt devices, remains in the bore and is still being accelerated after the front portion of the water slug begins to jet out of the bore, it tends to push against the jet that has left the bore. This tends to distort, degrade, and brake-up the jet causing the jet to disperse relatively quickly after leaving the bore and result in a reduced forward speed of the jet. Therefore, in order to use such means to render safe explosive devices, these systems must be placed within proximity of the explosive devices.